Method for producing a lubricating oil



METHOD FOR FRODUCING A LUBRICATING OIL l Filed-Sept. 21. 1955 jUIflitedStaSPnfO lmamon Fon PRonUcrNG A LUBRICATING on.

Edward L. Cole, Glenham, William E. Skelton, Beacon,

and Richard K. Meyers, Wappingers Falls, N.Y., assignors to The TexasCompany, New York, N.Y., a corporation of Delaware Application September21, 1955, Serial No. 535,626

6 Claims. (Cl. 208-97) This invention relates to a method of impartinglubricating characteristics to a cycle gas oil extract. Moreparticularly, the invention concerns the process of alkylating andsubsequent light hydrorening of a cycle gas oil solvent extract in orderto impart lubricating properties thereto.

The term cycle gas oil as used herein designates a material obtainedduring any cracking process such as thermal cracking and the variouscatalytic cracking procedures, for instance, xed bed, moving bed and uidcatalytic cracking operations. In these cracking operations a gas oilstock is subjected to treatment from which several hydrocarbon fractionsare obtained. The heavier Cycle gas oil has a high aromatic content and,from an economic standpoint, the aromatics are advantageously removed bysolvent extraction prior to the introduction of the material into thefeed line. Aromatic removal from the cycle gas oil is brought aboutusually by countercurrent solvent extraction using solvents such asfurfural, phenol, Chlorex (beta,betadichloroethyl ether) and the like.In accordance with the present invention furfural is the preferredsolvent from an economic standpoint. The highly aromatic extractsproduced are, in the solvent refining of the cycle gas oil,nonlubricating materials.

The alkylation of mineral lubricating oil extracts to improve thecharacteristics of the oil, notably the viscosity-temperaturecharacteristics, is known in the art. It is also known to employ lighthydrogenation to improve the viscosity indices of mineral lubricatingoil extracts. There are, however, distinct differences between cycle gasoil extracts and mineral lubricating oil extracts. The main differenceslie in the greater aromaticity of the cycle gas oil extract, the highermolecular weight and the higher boiling range of the lubricating oilextract. The present invention is concerned with the improvement of acycle gas oil extract as distinguished from a mineral lubricating oilextract. In accordance with the present invention we have found thatalkylating and subsequently light hydrorening a cycle gas oil extractyields a suitable lubricating oil having an exceptionally low solidpoint and carbon residue with accompanying excellent oxidation stabilityand an' improved viscosity index. s The alkylation of the cycle gas oilextracts is preferably carried out with olen material within the rangeof naphtha to gas oil olefns with the resulting conversion of thecomparatively light extract to that of a lubricating oil stock. Althoughthe molecular weight is suiciently increased by the alkylation process,it does not increase the viscosity index suiciently to produce avaluable lubricating oil. v'1`hesealkylated stocks do, however, showasurprising resistance to oxidation with very low varnish propensitiesand, when blanded with other lubricating oils, served to reduceoxidation and varnishing tendencies of the blend to a great extent. Inorder to utilize the good features ofthe alkylated cycle gas oilextract, light hydrorening was carried out in accordance with thepresent invention to produce a valuable oil having a surprisingly lowsolid point, low carbon residue with an improved viscosity index andstill retaining the good oxidation resistance and anti-varnishproperties of the alkylated extract.

The product of the present invention has characteristics which make itparticularly valuable as a lubricant at low temperatures. It is alsovaluable as a jet engine oil blending component, a hydraulic uid and anautomatic transmission iiuid component.

In further explanation of the invention, the solvent extract of a cyclegas oil is alkylated in the presence of a catalyst with olens or otheralkylating materials such as alkylhalides or alcohols ranging inmolecular weight from about 100 to 300. Examples of alkylation catalystuseful in accordance with the present invention are the well knownFriedel-Crafts catalysts including hydrogen tluoride, boron tritluoride,aluminum chloride, ferrie chloride and stannic chloride. Also used ascatalysts are phosphorus pentoxide, kieselguhr and sulfuric acid. Thepreferred alkylation catalyst is hydrogen uoride on the basis of asuperior yield with its use. It has been found that this catalyst (HF)functions best when high ratios, rang ing from 0.3 to 0.5, of hydrogenuorideto hydrocarbon (extract+olen) are used. When this is done, bothyield and product quality were superior. The preferredalkylating'materials employed are alpha oletins. A good source of thesealpha olens is a highly olenic naphtha fraction obtained by reaction ofsynthesis gas (H2-C0) in the presence of an iron catalyst andsubsequently freed of oxygenates by the conventional procedures such aspassing the olefinic material over -a deoxygenating catalyst, forexample, a highly absorptive synthetic hydrous magnesium silicate oralumina at a raised temperature or by adsorption with silica gel atambient temperatures. The temperature range over which alkylation occurswill vary with the catalyst used. In the preferred method of alkylation,using HF as the catalyst, the broad temperature range is from l0 to Y150F. whereas the preferred range is from 25 to 110 F.

The alkylate formed is thereafter sufficiently hydrogen ated with acatalyst selected for electing saturation of alkylated aromatic ringswithout appreciable concomitant excessive destructive hydrogenation.Examples of mild hydrogenation catalysts which can be used are asfollows:

Various nickel-tungsten sulde mixtures, molybdenum sulfide, cobaltmolydate, molybdena alumina, chromia alumina, supported noble metalcatalysts, for example, platinumized charcoal or a catalyst comprisingalumina, platinum and a combined halogen. Of the foregoing catalysts thenickel-tungsten suldes are preferred.

l the charge materials.

The present invention will be better understood by reference to theaccompany drawing wherein the single figure is a ow diagram of theprocess in accordance with the invention.

In general, two initial procedures were used in mixing The first,lhereinafter known as procedure a, was the mixing of the alkylationcatalyst with the aromatic extract and then adding the olefin slowly.The second alternative procedure, hereinafter referred to as procedureb, involved the mixing of the extract and olen and thereafter adding thealkylation catalyst slowly. Procedure a is preferred as its productsexhibit slightly lower varnishing tendencies. After adding allcomponents, stirring is continued in the alkylation reactor long enoughto insure that the reaction has progressed to equilibrium, usually fromabout 8 to 24 hours in batch operation although some? what shorterperiods may .also be used. The catalyst is then separated and thealkylated oil layer is causticneutralized `and washed. The product isthen dried, flashstabilized by distillation at temperatures from 250 to3.507 F. at from l-2 mm. pressure to yield an alkylate ready to undergohydrogenation.

For light hydrorening, the alkylate oil, with or without diluent, suchas cyclohexane, and hydrogenation catalyst are charged to an autoclaveand the system is flushed with hydrogen to remove air. The autoclave isthen pressured cold withhydrogen to a point commensurate with thecalculated desired pressure at the operating temperature. The pressurerange for this type of light hydroreiining in accordance with thisinvention is from about S to 5000 p.s.i.g. and the hydrogen consumptionranges :terrazas lIt can be seen from theabove Table II that these imaterials are excellent with respect to varnish formation.

fromabout 400 to 1500 cubic feet per barrel of alkylated extract. Theautoclave is continuouslyagitated and heated until the hydrogen take-upas'measured by a pressure drop, has ceased. The temperature maintainedduring the reaction ranges from about 500 to 800 F., however, thepreferred range is from 600 to 700 F. Pressure was maintained by theaddition of hydrogen from a high pressure source when necessary. The oilis thereafter ltered to remove the catalyst and stabilized at increasedtemperaturc and decreased pressure with nitrogen blowing.

The material prepared by procedure b produces somewhat more varnish andfor this reason procedure a is preferred. Nevertheless, the materialsformed by either procedure show surpringly low varnishing tendencies.

The low neutralization numbers of these materials after beingv subjectedto the Toettcher varnish test demonstrates their excellence with respectto oxidation stability.4

It is apparent from Table I that the alkylatedp'roducts do not exhibitcharacteristics which are particularly suited to a useful lubricant baseoil. The low Vl., high solid point and carbon residue of .alkylatedextract are undesirable in a lubricant.

The following table shows the pertinent data concerning the hydroreningof another alkylated cycle gas oil extract from a duid catalyticcracking unit. The extract was alkylated with a highly olenic naphthafraction rich in alpha olens and having a boiling range of 150 to 380F., obtained by the reaction of synthesis gas (H2-CO) in the presence ofan iron catalyst and thereafter freed of oxygenates by passing thematerial over silica gel at room temperature.

The following table shows the alkylation reaction conditions and thecharacteristics of alkylated furfural extracts of cycle gasoil from auid catalytic cracking unit. The material usedv to alkylate was a highlyolenic naphtha fraction rich in alpha olens and having a boiling rangeof 150 to 380 F., obtained by the reaction of a specic gravity (6U/60F.) of 1.006 and a boiling range of from about 520 to 650 F. Thecatalyst used for the alkylation step was hydrogen uoride.

TABLE I Products from Products from Procedure a Procedure b Charge Run 1Run 2 v.Run 3 Run t Extract/01cm; wt 1. 1 0. 28 0. 28 0. 28Catalyst/Glenn; wt... 0.63 0.51 0.51 0. 51 CatalystlHydrocarbon; 0. 0. 40. 4 0. 4 Tem erature, 32 25 35 105 Yiel wt. percent basis hydrocarboncharge 5 33. 8 34. 2 26 Sp Gr., Gil/60 F. 0. 9580 0. 9307 0. 9268 0.9364 SUS Vis. at 210 F 55.2 68. 8 78. 0 89. Solid Point, F +6 -8 0 +7Carbon Bes., percen 0.71 0. 61 0. 68 1. 15 Viscosity IndeL -99 -19 -3 -2The following table demonstrates the excellent proporties of alkylatedcycle gas oil extract with respect to resistance to'oxidation and lowvarnish forming tendencies. The particular test used in this case wasthe Toettcher varnish test which is described in U.S. Patent No.2,674,577, to Frederic C. McCoy, Bill L. Benge, Edwin C. Knowles, andCharles C. Towne, issued August 6, 1954.

TABLE Ill Charge to autoclave:

Oil, ml. 300 Cyclohexane, ml. 100 vlsickel-tungsten sulfide, g. 60Temp., F. 635 Pressure, p.s.i.g. 3000 H2 consumption, cu. ft./bbl'. 800

Charge Stabilized Product o. 932s .0256s 70.(7l 33.7 Car. Res., percent0.71 0.008 Viscosity Index -15 64. 5

The extremely low solid point and carbon residue coupled with theimproved viscosity index of the cycle gas oil extract as shown in TableIII make this product a useful lubricant particularly for lowtemperature lubrication.

Obviously, many modifications and variations of the invention, ashereinbefore set forth, may be made without departing from the spirit`and scope thereof and, therefore, only such limitations should beimposed as are indicated in the appended claims.

We claim:

l. A method for producing a lubricating. oil charac' terized by a lowcarbon residue and low solid point which comprises alkylating a cyclegas oil extract with olenic material within the'molecular Weight rangeof naphtha to gas oil olens to produce an alkylated extract charac-Aterized by a high solid point, a high carbon residue and a low viscosityindex, and thereafter subjecting the alkylated extract to hydrorening ata temperature in the range of from 500 to 800 F. and at a pressure inthe range of from 500 to 5000 p.s.i.g. 2. A method as described in claiml wherein the cycle gas oil extract is alkylated with alpha loletluswithin the molecular weight range of naphtha to gas oil oletins.

3. A method as described in claim l wherein the cycle gas oil extract isalkylated with a deoxygenated highly olefinic naphtha fraction, rich inalpha olefins, obtained by the reaction of hydrogen with carbon monoxidein the presence of an iron catalyst.

4. A methodasdescribed in. claim l wherein thealkylation is performed inthe presence of a hydrogen fluoride catalyst'wherein the ratio ofcatalystv to hydrocarbon is in; thesrange of from 0.3 to 0.5, and thetemperature is' in the rangeof from 25 to.1l0f F.

5. A: method. as described1 in claim 1 wherein thehy drogenaton takesplace at a temperature of from 600 to 2,549,111 Millendorf et al Apr.17, 1951 700 F. and at a pressure of from 1500 to 4000 p.s.i.g.2,673,175 Stratford Mar. 23, 1954 6. A method as described in claim 1wherein the hy- 2,707,713 Mattox May 3, 1955 drorening is carried out inthe presence of a nickel- 2,734,019 Miller etal. Feb. 7, 1956 tungstensulfide catalyst. 5 2,762,853 Jones et a1 Sept. 11, 1956 ReferencesCited in the le of this patent FOREIGN PATENTS UNITED STATES PATENTS665,008 Great Britain Jan. 16, 1952 2,141,593 Clarke et a1. Dec. 27,1938 665,058 Great Britain Ian. 16, 1952

1. A METHOD FOR PRODUCING A LUBRICATING OIL CHARACTERIZED BY A LOWCARBON RESIDUE AND LOW SOLID POINT WHICH COMPRISES ALKYLATING A CYCLEGAS OIL EXTRACT WITH OLEFINIC MATERIAL WITHIN THE MOLECULAR WEIGHT RANGEOF NAPHTHA TO GAS OIL OLEFINS TO PRODUCE AN ALKYLATED EXTRACTCHARACTERIZED BY A HIGH SOLID POINT, A HIGH CARBON RESIDUE AND A LOWVISCOSITY INDEX, AND THEREAFTER SUBJECTING THE ALKYLATED EXTRACT TOHYDROREFINING AT A TEMPERATURE IN THE RANGE OF FROM 500 TO 800*F. AND ATA PRESSURE IN THE RANGE OF FROM 500 TO 5000 P.S.I.G.